window.onscroll = function() {
    scrollFunction()
};  
function scrollFunction() {
console.log(121);
if (document.body.scrollTop > 20 || document.documentElement.scrollTop > 20) {
    document.getElementById("btnTop").style.display = "block";
} else {
document.getElementById("btnTop").style.display = "none";
}
}  
function returnTop() {
document.body.scrollTop = 0;
document.documentElement.scrollTop = 0;
}

var swiper = new Swiper('.swiper-container', {
    slidesPerView: 3,
  spaceBetween: 30,
  centeredSlides: true,
  loop: true,
  autoplay: {
    delay: 2000,
    disableOnInteraction: false,
  },
  pagination: {
    el: '.swiper-pagination',
    clickable: true,
  },
  navigation: {
    nextEl: '.swiper-button-next',
    prevEl: '.swiper-button-prev',
  },
});